1) to be possessed of unfailing strength
1a) to be strong, to suffice, to be enough
1a1) to defend, ward off
1b) to be satisfied, to be contented
Part of Speech: verb
Citing in TDNT: 1:464, 78
Apparently a primary verb (but probably akin to G142 through the idea of raising a barrier); properly to ward off, that is, (by implication) to avail (figuratively be satisfactory): - be content, be enough, suffice, be sufficient.
These two sites give similar information, with the definition from several dictionaries and statistics on the use of the word.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root ἀρκέω; click on the second column to search for that grammatical form of the root ἀρκέω; click on the third column to search for that word and grammatical form; click on the total to search for the root ἀρκέω.